This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Scientists at Cornell University have found a human genetic element in a poxvirus and discovered that it is both an important gene for brain function and a jumping gene capable of moving and inserting itself into genomes. A study published in Science reports that the gene, called BC200, combines characteristics never before seen together.
BC200 is primarily expressed in neurons but originated millions of years ago from a transposon, or "jumping gene," a noncoding genetic element known for its ability to move and insert itself into genomes. Transposons can insert blocks of DNA into a gene and disrupt its function, leading to disease. But in the long term, they can be a constructive force in evolution, regulating or assembling new beneficial genes.
While transposons account for half of human DNA, most are inactive, with only a very small number remaining mobile and able to replicate within genomes. Until now, no one had observed a human gene that is both mobile and required for bodily functions. "Genes that come from transposable elements and that are repurposed for cellular functions are typically no longer transposable," said Cedric Feschotte, a senior author of the study.
"BC200 was itself created from a mobile element but has retained its mobility and yet it is also clearly serving a cellular function. Somehow evolution hasn't been able to untangle these two things." Co-authors include Cheng Sun, professor of evolutionary genomics at Capital Normal University in Beijing, China; and Ellen Pritham, who was an assistant professor at the University of Texas at Arlington when the work was done. The researchers first identified BC200 in 2010, when Feschotte was a faculty member at University of Texas, Arlington, and Cheng was a postdoctoral researcher in Feschotte's and Pritham's joint lab.
At the time, Cheng was investigating human transposons in viral genomes using specialized software and genome databases, and he found two insertions of BC200 in a molluscum contagiosum virus (MCV), an infectious but largely benign human poxvirus that causes warts. Though the team recognized the importance of the discovery, they didn't write a paper on it at the time. Feschotte and Cheng recently met at a conference, and Cheng mentioned that he and his graduate student, Pu Gao, the paper's first author, had resurrected the project.
"I can't believe we never got scooped on this," Feschotte said. A progenitor of BC200 was co-opted into a common primate ancestor from an ancient transposon roughly 40 million years ago and has jumped to MCV twice within modern human history (since the era of Homo sapiens), about 100,000 years ago. There have been a few other documented cases of transposable elements in other species inserting themselves into viruses.
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